The Cartwheel galaxy (also known as ESO 350-40) is a lenticular galaxy about 500 million light-years away in the constellation Sculptor.
It is about 150,000 light years across, slightly larger than the Milky Way. It has a mass of about 2.9–4.8 × 109 solar masses, and rotates at 217 km/s.
It was discovered by Fritz Zwicky in 1941. Zwicky said his discovery was "one of the most complicated structures awaiting its explanation on the basis of stellar dynamics".
The Cartwheel galaxy shows radio and optical spokes, but they are not the same spokes.